Dryer appliances generally include a cabinet with a drum mounted therein. In some dryer appliances, a motor rotates the drum during operation of the dryer appliance, e.g., to tumble articles located within a chamber defined by the drum. Dryer appliances also generally include a heater assembly that passes heated air through the chamber of the drum in order to dry moisture-laden articles disposed within the chamber. This internal air then passes from the chamber through a vent duct to an exhaust conduit, through which the air is exhausted from the dryer appliance.
In order to provide enhanced control of a clothes dryer appliance, it can be desirable to know one or more conditions (e.g., the moisture content) of clothing being dried by a dryer appliance. For example, the dryer can be operated until it is sensed that the moisture content of the clothing has fallen below a desired amount. The heater or other appropriate components of the dryer appliance can then be de-energized or otherwise controlled accordingly.
Certain existing dryer appliances use two metal rods in parallel or a combination of rods and the drum surface as a sensor to detect available moisture in the clothing. Other sensors for detecting temperature and relative humidity can be added as well to sense internal air properties. These sensors typically receive excitation power from the dryer control board via a physical connection, such as electrical wires. Therefore, the sensors are frequently placed on a non-rotating component of the dryer, such as a door or a fixed back wall.
Placement of the sensors on the rotating components of the dryer, such as the drum or associated lifters or baffles, can result in obtaining more accurate readings at a higher frequency. However, placement of the sensors on the rotating components can present additional problems. For example, wireless communication systems may be required for transmitting data from rotating components to the non-rotating components. However, very little clearance is generally provided or desired between the drum and the cabinet. It can be difficult to mount components proximate to the drum without increasing the overall cabinet size or volume.
Therefore, improved dryer appliances and sensor assemblies thereof are needed.